Liners are commonly used to repair and/or reinforce ruptured or weak areas in pipeline networks such as sewer systems and the like. Conventional approaches for installing a liner into a pipeline typically involve excavation to expose the pipeline. However, as will be appreciated, excavation methods are expensive, time consuming and disruptive.
To avoid the problems associated with excavation, “cure-in-place” pipeline repair technology has been developed to allow pipelines to be repaired or reinforced without requiring disruptive excavation. During “cure-in-place” pipeline repair or reinforcement, a resin impregnated liner is delivered to the pipeline section to be repaired or reinforced, is brought into contact with the interior surface of the pipeline section and is maintained in place at that location until the curing process is complete.
Several approaches for positioning “cure-in-place” liners within a pipeline are used in the industry. For example, the liner can be pushed along the pipeline to a desired location using a series of push-rods. As will be appreciated, transitional areas along the pipeline such as bends and fittings create significant delivery problems, as the push-rods may be unable to effectively move beyond these transitional areas.
Alternatively, and more commonly used in the industry, the liner may be pulled along the pipeline to a desired location using a winch and cable. For example, U.S. Pat. No. 6,691,741 to Manners discloses an installation assembly for installing a liner in a pipeline comprising an inner bladder having an installation end and a retrieval end. An outer bladder surrounds the inner bladder. The ends of the inner and outer bladders are coupled together adjacent the installation end. The inner bladder is coupled to an air source at the retrieval end and the outer bladder adjacent the retrieval end is free. Following installation and curing of the liner, the bladder assembly is retrieved by pulling on the retrieval end of the inner bladder, and upon retrieval, the outer bladder is inverted.
Inversion delivery, wherein a liner is unrolled through itself by applied pressure as it projects forwardly into a pipeline, has also been described. For example, U.S. Pat. No. 4,366,012 to Wood discloses a method of impregnating the inner absorbent layer of a long flexible tube with a curable resin. During the method, a mass of the resin is introduced into one end of the tube. A window is formed in the impermeable outer layer of the tube at a distance from the resin mass. A vacuum in the interior of the tube is drawn through the window and concurrently the resin mass is pushed toward the evacuated region by passing the tube between a pair of squeezing members. When the flowing resin reaches the vicinity of the window, the window is sealed. Another window is formed in the tube farther downstream of the previously formed window. A vacuum is drawn through the new window while the squeezing members force the resin to flow toward the newly evacuated region. The procedure is repeated until the resin has spread through the entire inner absorbent layer of the tube.
Improvements are generally desired. It is therefore at least an object to provide a novel liner assembly for pipeline repair or reinforcement and a novel method of installing the same.